“Long-lived individuals have a greater number of teeth;”[87] which is as much as to say that “the having a greater number of teeth is a sign of longevity.” This prejudice is to be found repeated by many authors subsequent to the epoch of Hippocrates, and among these by Aristotle and Pliny. Not even the greatest men are infallible; there is, therefore, no reason to be scandalized if Hippocrates should really have fallen into such an error. Anyhow, it should be observed that only the first and the third book on _Epidemics_ are held to be really authentic, while the other five were probably compiled by other doctors of the school of Hippocrates who did not limit themselves merely to gathering together the many isolated notes and observations left in writing or derived from the oral teachings of their master, but took it upon themselves to introduce into the compilation something of their own besides. It is, therefore, anything but certain that the above-mentioned error is really to be attributed to Hippocrates. The probable origin of this prejudice, which certainly originated among the people and was afterward accepted by the doctors, is easily to be guessed at. Individuals blessed with dental arches of remarkable beauty and perfection may sometimes convey the impression of having a greater number of teeth than others, for those two rows of regular white teeth, close to one another, strike the optic sense much more vividly than teeth of the ordinary kind. This impression is somewhat analogous, at least as regards color—to the optical illusion which causes a white circle to appear larger than a black one of equal diameter. Now, without doubt, individuals with a perfect denture are mostly healthy and well constituted, and, therefore, live longer, in general, than others. It is also to be noted that these people usually keep all their teeth to a more or less advanced age; and there is no doubt that among adults of the same age, those who have a less number of teeth, by reason of having lost several of them, are, in general, individuals whose organic constitutions are less good, whose health is less satisfactory, and who are, therefore, destined in all probability to live a shorter time than the others. It is, therefore, perfectly true, _but only in a certain and very limited sense_ that “long-lived individuals have a greater number of teeth.” Geist-Jacobi, perhaps in order to dissipate the erroneous signification of the Hippocratic proposition cited above and to place in evidence that part of it which may be true, has thought well to translate it thus: